Thin sheet glass, commonly referred to as microsheet, is well known in the glass art. The glass sheets have a thickness less than 0.5 mm, a standard thickness being in the range of 0.3 to 0.4 mm. Microsheet glass is used for such diverse purposes as protective covers for satellite solar cells, laptop LCDs, and glass-plastic laminates.
Mirrors are commonly produced by applying a highly reflecting film or coating of, for example, silver or aluminum, over one flat surface of a glass sheet. Light rays pass through the glass sheet and are reflected back to create the familiar image. Thus, the effective light path in the glass sheet is twice the thickness of the glass sheet.
The present invention is particularly concerned with a rearview mirror such as used in vehicular transport means on sea, on land, or in the air. A problem of long standing is that of visual discomfort, and loss of object definition, created by reflection of certain radiation. The reflection of illumination from a mirror, particularly at night, can be particularly serious. This has led to special mirrors that can be tilted at night. A similar effect occurs with reflected sunlight, especially when the sun is just rising or setting.
It has been reported that this problem largely arises from a relatively narrow portion of the spectral energy distribution in light reflected by a mirror. In terms of color, this is the yellow region which lies primarily between wavelengths of 565 and 595 nm. The red, green and blue regions, which lie outside this wavelength range, appear to provide little or no contribution to the problem.
It is then a primary object of the present invention to provide a reflecting mirror that is improved with respect to the visual discomfort and object blurring that tends to occur with reflected illumination and sunlight.
It is another object to provide a glass that removes, in part at least, the yellow color region in reflected light.
It is a further purpose to provide this selective color effect in glass of microsheet thickness.
It is still another purpose to provide a glass having this desired color absorption effect, in conjunction with viscosity properties that enable the glass to be drawn as microsheet, that is in a thickness less than 0.5 mm.